Field of the Invention
The present embodiment relates to a leveling plate and a thrust bearing device using the same.
Description of the Related Art
Rotary machines including various turbines such as a steam turbine, motors, pumps, and the like utilize a thrust bearing device which supports a rotary shaft in an axial direction (see Japanese Patent Laid-Open Nos. 2013-50144 and 7-224843). In such a thrust bearing device, a thrust pad which is in contact with a rotary shaft is supported by a member referred to as a leveling plate. The leveling plate is provided in a plural number in a circumferential direction centering on the rotary shaft so as to follow deformation of the thrust pad thereby facilitating the uniformization of load to which each thrust pad is subjected. In a case of conventional art, contact portions at which leveling plates come into contact with each other are radially provided with a center of the rotary shaft as a starting point. That is, leveling plates which are disposed in an alternating manner are in linear contact with each other at a contact portion which acts as a mutual force point.
However, in the case of a thrust bearing device including a conventional thrust pad, due to displacement of the thrust pad caused by inclination of the rotary shaft member and difference in the thickness of the thrust pad, change of posture, that is, inclination occurs in the leveling plate supporting the thrust pad. When such inclination occurs, a so-called lever ratio, which indicates a ratio of a distance from a first force point (second acting point) to a fulcrum, and a distance from a second force point (first acting point) to the fulcrum, changes from a ratio 1:1, which indicates an ideal state. This is attributable to the fact that a contacting portion extends radially between leveling plates. For that reason, if the height or the thickness differs in the axial direction between thrust pads, load to which the leveling plate is subjected becomes non-uniform. As a result of that, a problem arises in that the load to which the thrust pad is subjected also becomes non-uniform between thrust pads, which may lead to local contact between the thrust pads, as well as phenomena associated therewith such as wear and damage.
Accordingly, it is an objective of the present embodiment to provide a leveling plate which exhibits a small change in lever ratio even if inclination occurs in the leveling plate.
Moreover, it is an objective of the present embodiment to provide a thrust bearing device in which the uniformity of load applied to each member to be supported is improved by using a leveling plate in which change in lever ratio is small.